Method of and apparatus for carbonizing coal and like material



' y 21, 2 I. F. LAUCKS 1.713.8 0

METHOD OF AND APPARATUS FOR CARBONIZING COAL AND LIKE MATERIAL Filed June 23. 1920 2 Sheets-Sheet l MaY-Zl, 1929. LAUCKS 1,713,840

METHOD OF AND APPARATUS FOR CARBONIZING COAL AND LIKE MATERIAL Filed June-23, 1920 2 Sheets-Sheet 2 J 9? Riga aw/@25 .JFVL/W FAQ/aura,

Patented May 21, 1929.

UNITED STATES/PATENT OFFICE.

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r. Lacoxs, or SEATTLE, WASHINGTON, Assmnon, BY DIRECT AND MESNE ASSIGNMENTS, T0 OLD BEN COAL CORPORATION, OF CHICAGO, ILLINOIS, A CORPO- RATION OF DELAWARE.

METHOD AND APPARATUS FOR CARBONIZING COAL AND LIKE MATERIAL.

- Application filed June 23, 1920.- Serial Resume.

My present improvedmethod of carbonizing coal or like material relates more particularly to the handling of such a material for the purpose of driving off the volatile constitutents therefrom in a retort through which the materialf is passed by means of a screw. I am aware that it has heretofore been proposed to thus handle such material incidentally to coking or earbonizing processes, but so far as I am aware no such method has ever proved a practical success, for the reason. that the working conditions encountered have never heretofore been correctly analyzed, and their effect properly taken into consideration.

The difficulty, in other words, that has heretofore been invariably encountered when it has been attempted topass a material, such as coking coal, through a retort of the type in question, characterized by having an internal rotor with a spiral fin thereon, has been the packing of the material at one or more points in its path through the retort. Accordingly, an excessive amount of power has been required to operate such an apparatus, and unless the parts entering into the apparatus are of extremely 'heavy construction, they wil not withstand the consequent stresses. Sue blocking or clogging of the retort is furthermore objectionable, in that, in order that the gases which are given off may find an exit, it is necessary to preserve a partially vacant space in the thread of the rotor. Finally the; structure of the coke, where the material is thus subjected to excessive localized pressure, is unsatisfactory.

The primary object of the present improved method accordingly is to avoid this tendency to packor clog on the part of the material, by so controlling the application of heat to the retort as to insure that the material will, at all points throughout its progress through the apparatus, have proper frietional or adhesive contact, as the case may be, with the stationary'inr r wall of the retort and the moving outer wall of the rotor and the fin thereon, so that such material will be kept moving- Obviously if such condition can be obtained, the power required to turnthe rotor need not be excessive, and the apparatus need not be built to resist unusual stresses. To the accomplishment of the foregoing and related ends, the

invention, then, consists of the means andsteps hereinafter fully described and particularly pointed out in' the claims, the annexed drawing and the following description setting forth in detail certain mecha- A further object of the invention is to provide a form of screw retort in which the material is held in such away as to facilitate rapid and uniform heating.

Figure .1 is a vertical secti In said annexed drawing onal view, more or less diagrammatic in character, of a carbonlzing retort of the type in question, adapted for operation in accordance with my present invention. Figures 2, 3, 4 representations showing the and 5 are diagrammatic influence on the plastic zone of varying temperatures at the inner surface of the retort and the outer-sur face of the rotor.

When a cylindrical retort of the\type in hand is heated as usual on the outside, while .coal is being passed therethrough by means of a rotor with an external screw, the following changes may be observed as taking place in such coal.

As it enters the retort it is of course loose and granular. Upon gradually becoming warmed up, the outside surfaces of the particles first begin to be sticky or plastic, whereupon the pieces stick to one another and become agglomerated int 0 more or less of a mass. As this mass proceeds toward the hotter, portion of the retort,

the particles or pieces gradually become fused all the Way through, sometimes becoming almost fluid. Elimination of volatile matter takes place until the whole is formed into a plastic sticky mass that tends to stick to the walls of the retort, and of course to the surface of the screw as well.

That zone in the retort in' which the coal passing therethrough is plastic or fused in whole or in part is herein called which has the greater area.

However, as-tlie' mass thus moves forward under the impulsion of the screw, it gradually loses more volatile matter and be ins to stiffen, and finally when such volatile matter has been reduced to approximately twenty per cent, the material begins to set. 1

Now it is evident that this change will take place faster, the hotter the coal, and as the mass is propelled through the retort, the coal adjacent to the retort wall is subjected to the greater heat, and accordingly thus sets more quickly than the coal adjacent to the screw. Just as in the case of the material in its initial granular state, so, after it has set, the adhesion of such material against the retort wall becomes practically nil; that is, there is no real adhesion, the only obstacle to the movement of the material being that due to its coefficient of fric tion in slidin over iron. However, assuming, as state that the material sets adjacent the retort wall while it is still partially plastic adjacent to the screw, it will obviously adhere to the latter, and when this condition occurs, such material will not be propelled forward but simply turn around and around with the screw. More material will be brought up from behind before that adjacent to the screw has a chance to have its adhesion reduced by setting, and a blockade is thus formed which extends backward through the retort as long as coal continues to be fed, unless tremendous power is employed to move it on.

I have found, however, that if heat be applied to the retort and screw in such manneras to reverse the conditions just referred to, so that instead of the screw being a little cooler than the retort wall at the point in uestion, the screw is a little hotter, then just t e opposite effect will take place. The ultimate aim of any method to prevent the clogging of the screw is to increase the adhes1on.to the retort wall and to retain adhesion thereto until the material sets adjacent the screw. This is what my invention does. I accomplish this by completing the setting at the rotor wall while at the-opposite point in the retort wall the setting point is not quite yet attained. This may be accomplished by maintaining substantially equal temperatures at opposite points of the retort wall and rotor wall whereby to effect substantially the same conditions simultaneo hly at each of said points. But I prefer to asten the setting at the rotor wall by heating a given zone of the rotor to a greater temperature than the opposite retort wall. In addition to this, I may amplify the desired effect by. delaying the beginning of the plastic stage at the screw wall of the retort thereby relatively hastening the plastic stage at the outer wall. This is done by maintaining the screw cooler than the retort wall at thezone where material begins to become plastic, thuscreating a greater temperature gradient on the internal bound of the plastic zone than exists on the external bound.

y The various foregoing conditions are illustrated diagrammatically in Figs. 2 to 5 in which 12 represents coal in a plastic state between fragments of the rotor and the retort. The starting point and the end point of the plastic zone are indicated res ectively at 13 and 14; in the outer surface 0 the coal next to the retort and at 15 and 16 in the inner surface of the coal next to the rotor. In Fig. 2, the points 13' and 15 and the points 14 and 16 are shown respectively at the same levels, thus showing the plastic zone starting and ending at the same points along the rotor and the retort. In Fig. 3, the point 16 is below the point 14, thus showing the setting of the plastic coal at the rotor wall as occurring before setting of the plastic coal at the retort wall. the point 15 is above the point 13, thus showing the plastic zone as commencing later at the rotor than at the retort. 5 combines the conditions of Figs. 3 and 4. In other words, the coal, after passing through the plastic stage will become set In Fig. 4,-

Fig;

first adjacent to the screw, and will still have a certain tendency to adhere, to the retort 'wall. There will be no tendency for the material to form a blockade in this condition; on the contrary it will be propelled through the retort all the more easily. Of course if the condition could be realized of having the material set uniformly, and at the same time, both in that portion of the mass 'adjacent the retort wall and that adjacen't the screw, the material would be satisfactorily propelled through the retort, as it would then simultaneously lose its tendency to adhere ,to such retort wall and screw. H

Referring to the illustrative apparatus shown in the drawing, the cylindrical tubular casing or retort 1 is vertically disposed, and .the material is designed to be introduced at the bottom through feed intake openings 2, the coke being discharged at the top through discharge openings 3, and the gas and vapors being withdrawn through the openings 3*. However, it will be understood that I do not limit the application of my method to such particular disposition of retort, i. e. it may be horizontall disposed or at an angle if desired. Similarly, the direction of travel of the material need not be upwardly, in the case of such vertical retort, but such direction may be reversed, and the advantageous results hereinafter pointed out still attained. The ro-- tor 4 provided for thus moving*the material through retort 1 is tubular, as shown, and in the present instance has two spiral threads 5, although the number of threads is not an essentialfactor. The width of ameter the rotor shaft 1" and the width of the threads 5 are such that a comparatively narrow spiralpath '4" is left between the shaft of the screw and the inside surface of the retort 1. The helical threads fit inside theretort with only a small clearance.

A collar 4 on the rotor 4 between the.

openings 3 and 3 directs the coke to the openings 3. i

For the purpose of heating the retort around its circumference, the latter is enclosed in a furnace chamber 6 through which heated gases are passed in a direction the reverse of thatin which the material being treated is passed therethrough. Thus in the construction as shown, such heated s enter or areprovided (as by means 0 suitable gas burners) at one or more openings 7 at the upper end of the furnace chamber, pass thence downwardly and around the retort and escape through an opening 8 to the flue (not shown). As (previously stated, the rotor 4 is hollow, an located within the same I provide su plemental heating means, consistin as s own, of a gas burner 10 attache to the lower end of "a pipe 11 which at the same time serves to supply the combusti-ble mixture to said burner. It will be furthermore understood that said pipe is longitudinally movable to adjust the position of the burner 10 axially within the re- ,tort, and if desired a plurality of burners may be attached to said pipe spaced any desired distance apart.

In my invention I contem late heating uniformly circumferentially o the screw in any manner permitting the control ofthe temperature of any particular zone. Hence, I prefer to use the type of burner producing an annular ring of fire such as is produced b the annular burner 10. The opening in t is bu ner tends to draw in a larger volume of coo er air to cool the screw in the direction of the incoming coal.

B means of the burner thus located within t e rotor and adjustable axiall of the same, the wall of such rotor, and t e spiral threads thereon as well, may be directly heated and so brought to a higher temperature relatively to the temperature of the adjacent portion of the retort 1 than if the rotor were heated wholly by means of conduction from furnace chamber 6 through said retort and the intervening layer of material being treated. The latter,'it will be understood, is not a particularly good conductor of heat, and unless the diameter of the retort, and also the diameter of the rotor, as well as the thickness of the space between thetwo, be kept quite small, it is impossible in practice to maintain the rotor at a temperature nearly enough corresponding to that of the retort to prevent the clog ging action hereinbefore referred to. It may be possible, the parts, and strict limitation of the dimensions thereof, to maintain the temperature of the rotor close enough to that of the retort so that the material being treated will not set adjacent to the retort wall while it still sticks, due to its plastic condition, to the rotor. However, to insure successful operation, it is simpler to heat such rotor, as by a burner or equivalent means, within the same, to a tem erature slightly in excess of that of the a jacent portion of the retort wall at the point where the change from plastic coal to solid material takes place.

While I have stated, that I do not limit myself to a vertical retort nor to passing coal upwardl through said retort there are numerous a vantages to the herein described embodiment arjsing from the use of the described heating. means in a vertical retort to accomplish the purpose of m invention. By passing upwardly throng the hollow rotor-shaft the combustion gases from the burner 10, the lower portion of the retort can be kept cooler than the outer wall in order to delay the be inning of the plastic stage internally. T is utilizes a natural draft to advantage in the a paratus.

and frictional resistance which would otherwise be encountered thereon.

Likewise I have found that to embody my invention in the retort shown in the drawings is especially advantageous for coupling the retort to a so-called soaker as used in a two-stage coking process.

In experimental coking retorts employing a metallic internally heated screw it has been found thatsagging occurs if the retort be horizontal or approximately so. For this reason also I prefer that the retort be vertical or nearly vertical.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and steps herein disclosed, provided those stated by any of the following claims or their equivalents. be employed. v

I therefore particularly point ou and distinctly claim as my invention 1. The method of carbonizing coal which however, by proper. design of will become plastic upon suflicient heatin which consists in passing the same throng a cylindrical retort by means of a screw, and simultaneously applying heat by conduction to such material, the application of heat; being so regulated that at the zone where the plastic coal commences to' set the screw is hotter than the retort, whereby to conclude the setting process at the rotor while the plastic coal adheres to the retort.

2. The method of carbonizin coal which will become plastic upon sufiicient heating, which consists in passing the same through a cylindrical retort by means of a. screw and simultaneously applying heat by conduction to such material, the application of heat being so regulated that in the plastic zone a greater temperature gradient exists at the inner screw boundary thereof than at the outer retort boundary, whereby the plastic zone is narrower in the direction of passage of the coal at the inner boundary than at the outer boundary.

3. The method of car'bonizing coal which will become plastic upon sufiicient heating, which consists in passing the same through a cylindrical retort by means of a screw and simultaneously applying heat by conduction to such material, the a! plication of heat being so regulated that t e retort wall is hotter than the opposite screw wall at the point where the'coal commences to become lastic adjacent the retort wall, and that in the plastic zone the screw wall in the direction of passage of the coal is heated hotter than the retort wall, whereby setting of the coal occurs adjacent the screw wall while the coal is still plastic adjacent the retort wall..

4. The method of carboni zing coal, which consists in passing the same throu h a heated cylindrical retort means of a screw, and simultaneously independently heating such screw at a oint ad acent the zone in which such materialsets to a temferature at least equalto the temperature 0 the retort wall at the opposite point.

5. In apparatus of the character described, the combination of an externally heated cylindrical retort, a screw for passing material through said retort, and inde endent heating means for said screw, sai means being concentrically arranged within said screw and axially adjustable whereby to control the temperature in a predetermined zone.

6. In apparatus of the character described, the combination of an externally heated cylindrical retort, a screw for passing material through said retort said screw being hollow, and independent heating means for said screw located within and axially adjustable of the same, said means being adapted to heat the screw uniformly circumferentially. 7. In apparatus of the character described,

' -the combination of a cylindrical retort, a

1 screw for passing material through said revapors and .yond said zone so as to .tric with the screw.

8. In apparatus of the character described, the combination of a cylindrical retort, a screw for passing material through said retort, said screw being hollow, and means for heating said screw located within the same, said means comprising an annular burner concentric with the screw. I

9. In apparatus of the character described, the combination ofa cylindrical retort, a screw for passing material through said retort, said screw being hollow, and means for heatin said screw located within and axially ad ustable of the same, said means being adapted to heat uniformly circumferentially of the screw.

10. The method of carbonizing coal which will become plastic upon suflicient heating, which consists in passing the same through a cylindrical retort by means of a screw, externally heating the retort, and simultaneously independently heating the screw to a temperature in the region of the plastic zone substantially the same ,as the temperature of the opposite portions of the retort wall, and such that at the plastic zone of the coal, the outer boundary thereof at the cooler end commences no further from the retort entrance than the corresponding point on the inner boundary of said plastic" zone.

11. A carbonizing apparatus comprising a screw retort consisting of a vertical tubular qasing the width of the screw thread being less than the pitch of said thread and said thread fitting id tubular casing closely whereby to form a narrow spiral path for the material, means for externally heating said tubular casing around its circumference, means in said screw for applying heat to the inner surface of said screw over a local area in the range of the zone in which the material becomesplastic, means to admit coal to the cooler end of said path, and means to permit Withdrawal through said path of the uses evolved from said material, and sai screw thread exten'din from said coal admitting means to a point befeed the material through said "zone! 12. In apparatus of the character described, the combination of an externally heated cylindrical retort, a screw for passing material, through saidretort u 11 relative rotation between said retort an said screw, said screw being hollow, and independent local heating means for said screw located in an intermediate portion in said screw, said heating means being adjustable to shift the relative local application of heat from one region to another along said screw.

. 13. In apparatus offthe character described, the combination of a vertical retort, a screw extending substantially through said retort for passing material upwardly thercthrough upon relative rotation between said retort and said screw, said screw being hollow,'and independent local heating means for said screw located in an intermediate portion in said screw, said heating means being adjustable to shift the relative application of heat from one location to another along said screw.

14. In apparatus of the character desaid retort and said screw, said screw being- 15 hollow, and indelpcndent local heating means for said screw ocated therein 111 an intermediateportion thereof about which the material becomes plastic.

Signed by me, June, 1920.

IRVING F. LAUCKS. 

